Major Heat (Dashu) 大暑
The solar term
The hottest time of the year, humid and heavy, with frequent thunderstorms. For the crops it is the time of most sun and warmth, and of fastest growth.
| Year | Major Heat |
|---|---|
| 2026 | July 23 |
| 2027 | July 23 |
| 2028 | July 22 |
| 2029 | July 22 |
| 2030 | July 23 |
Dates are for China time (UTC+8); in other time zones the term may fall on a different day.
The three pentads
Each solar term lasts about fifteen days and is divided into three pentads of five days, each named after a sign in nature. In 2027:
Fireflies rise from damp grass 腐草為螢from July 23
Fireflies rise out of the grass. They lay their eggs in the damp soil under dead grass, so the ancients believed fireflies were born from rotting grass.
The earth is damp, the air heavy 土潤溽暑from July 28
The ground is damp and the air is thick and hot.
Great rains fall 大雨時行from August 2
Heavy rains fall from time to time. As they ease the damp heat, they are the first hint of autumn.
Hexagrams
In the table of the Tang monk Yixing’s Dayan calendar (recorded in the New Book of Tang), the three pentads of Major Heat belong to three hexagrams:
- first pentad10 Lü (Treading)Duke
- second pentad33 Dun (Retreat)Sovereign
- third pentad32 Heng (Endurance)Marquis
The second, Dun (Retreat), is one of the twelve sovereign hexagrams (十二辟卦), which trace the waxing and waning of yin and yang through the year. It stands for the sixth month of the traditional calendar: two yin lines below, as yin grows and yang withdraws.
Separately, the twenty-four lines of Kan, Zhen, Li and Dui govern the twenty-four solar terms in turn; Major Heat belongs to Li, nine in the third place.
The hexagram calendar marks the season. It says nothing about fortune and has no bearing on a hexagram you cast. See sources and method.